Deicer zones with heater-enhanced borders

ABSTRACT

An ice protection system comprises deicing zones wherein each zone includes an envelope with an electrothermal heater layer Adjacent envelopes have edge regions flanking shared interzone borders. These edge regions can be configured to provide a higher heating power than the rest of the envelope so as to enhance deicing at the borders.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIM

This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/623,047, filed Apr. 11, 2012, entitled “DEICER ZONES WITH HEATING-ENHANCED BORDERS”, and to Application No. 61/623,050, filed Apr. 11, 2012, entitled “DEICER ZONES WITH SHEDDING-ENHANCED BORDERS”, both of which are incorporated herein by reference in their entirety.

BACKGROUND

An aircraft will typically include an ice protection system to prevent excessive ice accumulation on its wings, stabilizers, engine inlet lips, and/or pylons. The ice protection system can incorporate an array of contiguous deicing zones associated with areas surrounding the leading edge. Each deicing zone can include envelope having an electrothermal layer which converts electric power to heat for deicing of the associated area.

SUMMARY

According to one embodiment, an ice protection system comprising a first set of contiguous deicing zones is disclosed. In this embodiment, each deicing zone comprises an envelope defining an ice-protection area; at least two of the envelopes are adjacent and share a common interzone border; each of the adjacent envelopes includes an edge region flanking the interzone border; and the edge region of at least one of the adjacent envelopes is configured to enhance ice deicing at the interzone border by providing a higher heating power density than the rest of the envelope.

DRAWINGS

FIG. 1 shows an aircraft having several surfaces protectable by the ice protection system;

FIGS. 2-3 shows flattened views of the ice protection system wherein interzone borders extend in a spanwise direction;

FIGS. 4-6 show standard power-supply procedures for the deicing zones of the ice protection system;

FIGS. 7A-7C show some possible edge-power-density profiles for the deicing zones of the ice protection system;

FIGS. 8A-8C, 9A-9C, 10A-10C, 11A-11C, 12A-12C, 13A-13C, 14A-14C, 15A-15C, 16A-16C, and 17A-17C show some heater-element constructions for achieving the edge-power-density profiles shown in FIGS. 7A-7C;

FIG. 18 plots the increase in per-episode power versus the decrease in overall deicing power;

FIG. 19A shows an alternate version of the ice protection system wherein the interzone borders instead extend in a chordwise direction;

FIG. 19B shows another alternate version of the ice protection system wherein the interzone borders instead extend in a chordwise direction; and

FIG. 19C shows still another alternate version of the ice protection system wherein the interzone borders instead extend in a chordwise direction.

DESCRIPTION

Referring to FIG. 1, an aircraft 10 can comprise fuselage 11, wings 12, horizontal stabilizers 13, a vertical stabilizer 14, engines 15, and pylons 16. The wings 12 are the aircraft's primary lift providers. The horizontal stabilizers 13 prevent up-down motion of the aircraft nose, and the vertical stabilizer 14 discourages side to side swinging. The engines 15 are the aircraft's thrust-providing means and the pylons 16 serve as underwing mounting means for the engines.

Referring to FIGS. 2-3, each wing 12, stabilizer 13-14, engine 15, and/or pylon 16 can be viewed as having an ice-susceptible surface 20 with a leading edge 30. The airstream A first encounters the leading edge 30 and then travels in a fore-aft direction therefrom.

The surface 20 is provided with an ice protection system 40 comprising an ice protection array 50 and a controller 60 operably connected to the array 50. The illustrated ice protection array 50 comprises a first set 100 of contiguous deicing zones 101-103, a second set 200 of contiguous deicing zones 201-203, and an anti-icing zone 310. The anti-icing zone 310 will usually coincide with the leading edge 30 and can be positioned between the fore zone 101 of the first deicer set 100 and the fore zone 201 of the second deicer set 200.

While the surface 20 appears flat in the drawing, this is simply for ease in illustration and explanation. In most instances, the surface 20 will have a curved profile wrapping around the leading edge 30 of the associated aircraft structure. If, for example, the ice-susceptible surface 20 is on a wing 12 or a horizontal stabilizer 13, the deicing zones 101-103 could be located on upper portion of the wing/stabilizer and the deicing zones 201-203 could be located on its lower portion. If the surface 20 resides on the vertical stabilizer 14 or one of the pylons 16, the deicing zones 101-103 could occupy its rightside portions and the deicing zones 201-203 could occupy its leftside portions. If the surface area 20 is on one of the engines 15, the deicing zones 101-103 could be situated on inner lip portions and the deicing zones 201-203 could be situated on outer lip portions.

The deicing zones 101-103 in the first deicer set 100 each comprise an envelope 111-113 defining an ice protection area 121-123. Each envelope 111-113 includes an electrothermal heater layer 131-133 which converts electric power to heat to deice the corresponding ice-protection area 121-123. The envelopes 111-113 can comprise further layers (e.g., layers 141-143, layers 151-153, etc.) surrounding the heater layers 131-133 for thermal transfer, electrical insulation, and/or protection purposes.

The envelopes 111-112 share a common interzone border 160 and the envelopes 112-113 share a common interzone border 170, which both extend generally in a spanwise direction perpendicular to the airstream direction A. The interzone border 160 is flanked by an end region 161 of the envelope 111 and an end region 162 of the envelope 112. The interzone border 170 s flanked by an end region 172 of the envelope 112 and an end region 173 of the envelope 113.

The envelope 111 has a non-common (e.g., fore) border 180 adjacent its edge region 181 and the envelope 113 has a non-common (e.g., aft) border 190 adjacent its edge region 193. The border 180 and the border 190 also extend generally in a spanwise direction perpendicular to the airstream direction A.

The deicing zones 201-203 in the second deicer set 200 include similar envelopes 211-213 defining ice protection areas 221-223 and including envelope layers (e.g., layers 231-233, layers 241-243, layers 251-253, etc.). They also include an interzone border 260 (flanked by envelope edge regions 261 and 262), an interzone border 270 (flanked by envelope edge regions 272 and 273), a fore border 280 (adjacent envelope edge region 281), and an aft border 290 (adjacent envelope edge region 293). The interzone border 260, the interzone border 270, the fore border 280, and the aft border 290 extend generally in a direction perpendicular to the airstream direction A.

The anti-icing zone 301 can include an envelope 311 defining an ice protection area 321, housing an electrothermal heater layer 331, and including additional envelope layers 341 and 351. The anti-icing zone 310 can be bounded by borders 160 and 260 and flanked by envelope edge regions 161 and 261.

Referring to FIGS. 4-6, some possible power-supply procedures for the ice protection system 40 are shown. In each of these procedures, electrical power is episodically (not constantly) supplied to a heater for short time periods. The episode extent is selected so that enough heat is provided to loosen accumulated ice for sweeping away by the ensuing airstream. The episode-to-episode interlude is chosen so that an appropriate amount of ice accumulates therebetween. Although these time durations will vary depending upon several factors, an episode will ordinarily last about five to ten seconds and will usually be less than twenty seconds. And the interlude between episodes is generally greater than ten seconds.

In a zoned electrothermal deicing procedure, the power-supply episodes are executed in a staggering schedule so as to minimize power-draw spikes. The heaters' episodes are collectively viewed in terms of time intervals t1-tn, with different heaters being supplied power during different intervals. A cycle is completed when a power-supply episode has occurred for each deicing zone.

In FIG. 4, each cycle includes six intervals t1-t6, with power being supplied to sequentially to zones 101-103 and then sequentially to zones 201-203. In FIG. 5, each cycle includes three intervals t1-t3, with power being supplied sequentially to zones 101-103 and sequentially to zones 201-203 at the same time. In FIG. 6, each cycle includes eight intervals t1-t8, with only one deicing zone being supplied power during some of the intervals (e.g., intervals t1, t4, t5, t8) and two deicing zones being supplied with power during other intervals (e.g., intervals t2, t3, t6, t7).

The anti-icing zone 301 is continuously supplied with power in all of the illustrated power-supply procedures. This continuous supply of electrical power is intended to persistently heat the corresponding ice protection area 311 so that ice never even forms thereon. The use of such an anti-icing approach along a leading edge is considered customary in airfoil ice protection.

As was indicated above, the envelope structures commonly include further layers (e.g., layers 141-143, layers 151-153, etc.) surrounding the heater layers 131-133, at least some of which are for electrical insulation and/or protection purposes. As such, envelope constructions can often hinder the transfer of ice-melting heat to edge regions of the deicing zones. This hindering is especially apparent when two adjacent deicer envelopes share a common interzone border (e.g., envelopes 111-112 sharing border 160, adjacent envelopes 112-113 sharing border 170, adjacent envelopes 211-212 sharing border 260, and adjacent envelopes 212-213 sharing border 270).

When designing a deicer envelope, the non-heating layers are generally optimized to provide adequate electrical insulation, sufficient environmental protection, maximum heat transfer, lighter weights, lower power draws, and longer lives. As such, trimming parameters along edge regions could compromise electrical insulation and environmental protection. Likewise, protracting parameters within non-edge regions could cause weight and power-draw concessions.

The ice protection system 40 addresses border-heat-hindrance issues by configuring envelope edge regions to enhance deicing at such interzone boundaries.

As shown in FIGS. 7A-7C, the deicing envelopes are configured so that interzone-border edge regions have a higher power. In FIG. 7A, an increased power density is provided to each edge region flanking an interzone border (i.e., edge regions 161-162, edge regions 171-172, edge regions 261-262, edge regions 271-272). In FIG. 7B, an increased power density is provided to only the edge regions of an intermediary zone (i.e., edge regions 162 and 172 of mid deicing zone 102, edge regions 262 and 272 of the mid deicing zone 202). In FIG. 7C, an increased power density is provided at only at edge regions of non-intermediate zones (i.e., edge region 161 of fore deicing zone 101, edge region 173 of aft deicing zone 103, edge region 261 of fore deicing zone 201, and edge region 273 of aft deicing zone 203).

As shown in the 8th through 13th drawing sets, the heating layers 131-133 of the deicing zones 101-103 can comprise heating elements 135-137 and the heating layers 231-233 of the deicing zones 201-203 can comprise heating elements 235-237. These heating elements can comprise conductive tracks printed, etched, laid, or otherwise posed in a heating pattern within the heating layers. Increased power density in the relevant edge regions can be achieved by tighter spacing, higher heights, and/or wider widths of the tracks.

As shown in the 14th through 16th drawing sets, the heating elements 135-137 and 235-237 can instead each comprise a single track printed, etched, laid, or otherwise posed in a solid heating pattern. The heating layers 131-133 and 231-233 can include bus bars (not shown) for supply and return of electric power to and from the solid heating pattern. Increased power density in the relevant edge regions can be achieved by higher resistance and/or higher heights of the single solid tracks.

An increased power density in envelope edge regions can translate into more power being used by a particular deicing zone during each episode. However, analytical results indicate that a slight increase in per-episode power can result in a dramatic decrease in total deicing time, and thus a remarkable reduction in overall power. As shown in FIG. 18, for example, an about 3% increase in per-episode power can correlate to an about 20% decrease in overall deicing power, an about 6% increase in per-episode power can correlate to an about 30% decrease in overall deicing power, an about 9% increase in per-episode power can correlate to an about 40% decrease in overall power, and an about 15% increase in per-episode power can correlate to an about 45% reduction in overall power.

As shown in FIGS. 19A-19C, the interzone borders 160 and 170 can instead or additionally extend in a chordwise direction generally parallel to the airstream direction A. In this case, the first set 100 can comprise an inboard deicing zone 101, a mid deicing zone 102, and an outboard deicing zone 103. The second set 200 can comprise similar inboard, mid, and outboard zones 201-203. Inboard borders 180 and 280, and outboard boards 190 and 290, can likewise extend in a chordwise direction, with the anti-icing zone 301 being position between fore edges of the deicing zones 101-103 and fore edges of the deicing zones 201-203.

Although the aircraft 10, the aircraft surface 20, the system 40, the array 50, the controller 60, the deicing zones 101-103, the deicing zone 201-203, and/or the anti-icing zone 301 have been shown and described with respect to a certain embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. Specifically, for example, ice protection systems with more or less deicing and/or anti-icing zones are feasible and foreseeable. And while a particular feature of the aircraft 10 or the system 40 may have been described above with respect to some of the illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous.

REFERENCE NUMBERS 10 aircraft/outboard 11 fuselage 20 ice susceptible surface 12 wings 30 leading edge 13 horizontal stabilizers 40 ice protection system 14 vertical stabilizers 50 ice protection array 15 engines 60 controller 16 pylons 100 first set of deicing zones 200 second set of deicing zones 101 fore/inboard deicing zone 201 fore/inboard deicing zone 102 mid deicing zone 202 mid deicing zone 103 aft/outboard zone 203 aft/outboard deicing zone 111 fore/inboard envelope 211 fore/inboard deicer envelope 112 mid envelope 212 mid envelope 113 aft/outboard envelope 213 aft/outboard envelope 121 fore/inboard area 221 fore/inboard area 122 mid area 222 mid area 123 aft/outboard area 223 aft/outboard area 131 fore/inboard heating layer 231 fore/inboard heating layer 132 mid heating layer 232 mid heating layer 133 aft/outboard heating layer 233 aft/outboard heating layer 135 fore/inboard heating element 235 fore/inboard heating element 136 mid heating element 236 mid heating element 137 aft/outboard heating element 237 aft/outboard heating element 141 fore/inboard envelope layer 241 fore/inboard envelope layer 142 mid envelope layer 242 mid envelope layer 143 aft/outboard envelope layer 243 aft/outboard envelope layer 151 fore/inboard envelope layer 251 fore/inboard envelope layer 152 mid envelope layer 252 mid envelope layer 153 aft/outboard envelope layer 253 aft/outboard envelope layer 160 interzone border 260 interzone border 161 interzone-border edge region 261 interzone-border edge region 162 interzone-border edge region 262 interzone-border edge region 170 interzone border 270 interzone border 172 interzone-border edge region 272 interzone-border edge region 173 interzone-border edge region 273 interzone-border edge region 180 fore/inboard border 280 fore/inboard border 181 border edge region 281 border edge region 190 aft/outboard border 290 aft/outboard border 193 border edge region 291 border edge region 301 anti-icing zone 331 anti-icing heating layer 311 anti-icing envelope 341 anti-icing envelope layer 321 anti-icing area 351 anti-icing envelope layer 

1. An ice protection system comprising a first set of contiguous deicing zones; wherein: each deicing zone comprises an envelope defining an ice-protection area; at least two of the envelopes are adjacent and share a common interzone border; each of the adjacent envelopes includes an edge region flanking the interzone border; and the edge region of at least one of the adjacent envelopes is configured to enhance ice deicing at the interzone border by providing a higher heating power density than the rest of the envelope.
 2. An ice protection system as set forth in claim 1, wherein each envelope includes an electrothermal heater layer which converts electric power to heat to deice the corresponding ice-protection area.
 3. An ice protection system as set forth in claim 1, wherein each interzone border extends in a spanwise direction generally perpendicular to the airstream direction; and wherein: the adjacent envelopes comprise a fore envelope having an edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise an aft envelope having an edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise a mid envelope having a fore edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise a mid envelope having an aft edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope.
 4. An ice protection system as set forth in claim 3, comprising an anti-icing zone positioned fore of the first set of the deicing zones.
 5. An ice protection system as set forth in claim 3, comprising a second set of contiguous deicing zones; wherein: each deicing zone in this second zone comprises an envelope defining an ice-protection area; each envelope includes an electrothermal heater layer which converts electric power to heat to deice the corresponding ice-protection area; at least two of the envelopes are adjacent and share a common interzone border; each of the adjacent envelopes include an edge region flanking this interzone border (260/270); the edge region of at least one of the adjacent envelopes is configured to enhance ice deicing at this interzone border by providing a higher heating power density than the rest of the envelope; and each interzone border extends in a spanwise direction generally perpendicular to the airstream direction.
 6. An ice protection system as set forth in claim 5, comprising an anti-icing zone positioned fore of the second set of the deicing zones, the anti-icing zone being positioned between the first set of deicing zones and the second set of deicing zones.
 7. An ice protection system as set forth in claim 1, wherein each interzone border extends in a chordwise direction generally parallel to the airstream direction; and wherein: the adjacent envelopes comprise an inboard envelope having an edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise an outboard envelope having an edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise a mid envelope and wherein the inboard edge region of the mid envelope flanking the interzone border is configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and/or the adjacent envelopes comprise a mid envelope having an outboard edge region flanking the interzone border, this edge region being configured to enhance deicing at the interzone border by providing a higher heating power density than the rest of the envelope.
 8. An ice protection system as set forth in claim 7, comprising an anti-icing zone positioned fore of the first set of the deicing zones.
 9. An ice protection system as set forth in claim 7, comprising a second set of contiguous deicing zones; wherein: each deicing zone comprises an envelope defining an ice-protection area; each envelope includes an electrothermal heater layer which converts electric power to heat to deice the corresponding ice-protection area; at least two of the envelopes are adjacent and share a common interzone border; each of the adjacent envelopes includes an edge region flanking the interzone border; the edge region of at least one of the adjacent envelopes is configured to enhance ice deicing at the interzone border by providing a higher heating power density than the rest of the envelope; and each interzone border extends in a chordwise direction generally parallel to the airstream direction.
 10. An ice protection system as set forth in claim 9, comprising an anti-icing zone positioned fore of the second set of the deicing zones, the anti-icing zone being positioned between the first set of deicing zones and the second set of deicing zones.
 11. An ice protection system as set forth in claim 1, wherein the higher power density is achieved by tighter track spacing in the relevant edge regions.
 12. An ice protection system as set forth in claim 1, wherein the higher power density is achieved by higher track heights and/or wider track widths in the relevant edge regions.
 13. An ice protection system as set forth in claim 1, wherein the higher power density is achieved by higher-resistance track material in the relevant edge regions
 14. An ice protection system as set forth in claim 1, further comprising a controller which supplies electrical power episodically to each of the deicing zones, wherein the episode extent is less than twenty seconds, and wherein the episode-to-episode interlude is greater than ten seconds.
 15. An ice protection system as set forth in claim 14, wherein power is supplied sequentially to the deicing zones in the first set.
 16. An ice protection system as set forth in claim 14, wherein the power-supply episodes are executed in a staggering schedule.
 17. An ice protection system as set forth in claim 14, wherein the higher power density of the relevant edge causes an at least 3% increase in per-episode power for the deicing zone.
 18. An ice protection system as set forth in claim 17, wherein the higher power density of the relevant edge regions causes an at least 12% increase in per-episode power for the deicing zone.
 19. An ice protection system as set forth in claim 1, installed on an ice-susceptible surface, wherein the surface has a leading edge which an airstream first encounters and then travels in fore-aft direction therefrom, and wherein the deicing zones protect surface regions fore and aft of the leading edge.
 20. An aircraft comprising an ice-susceptible surface and an ice protection system as set forth in claim 1 installed on the ice-susceptible surface. 